When it comes to oracle we have ROW_NUMBER() OVER PARTITION BY statement but for Mysql it is still tricky to implement this one. As most probably we will use this implementation to limit data either descending/ascending order across groups.

Here you go with the similar implementation for your reference:

SELECT @row_number:=CASE WHEN @category=category
THEN @row_number+1 ELSE 1 END AS feeds,@category:=category AS category, content
FROM table1, (SELECT @row_number:=0,@category:='') AS t
ORDER BY category;